The program project brings together new data, a large group of experienced researchers from different countries, and a number of different modeling approaches to improve our understanding of retirement decisions. The overriding goal of the program project is to provide a far more complete, and perhaps more subtle, picture of what makes people reduce their work effort late in life than we have today. In view of the major issues faced by several countries with respect to the nature and future sustainability of old age security systems, a secondary important goal is to provide information that can guide policy makers in designing or changing these systems. The program project will contain six component projects and two cores. The component projects deal respectively with:(Blundell) the timing and coordination of retirement of spouses; (Hurd) the role of wealth accumulation or decumulation on retirement timing: (Gustman) the measurement of pension outcomes, including how much people actually know about their prospective pensions and about the changes in these pensions; (Rust) forward looking models of retirement timing, with special emphasis on D1 and SSI application; (Kapteyn) the role of health and workplace conditions in retirement decisions; (Kapteyn) integration of the findings and approaches in the first six projects, including an evaluation of the relative importance of different explanatory factors, the empirical success of different modeling approaches and several forms of new data that may aid in improving our empirical models. The data core provides overall programming support, maintains a number of important databases to be used by all component projects, and facilitates the sharing of software across projects. The administrative core facilitates interaction and guarantees a smooth administrative process. Integration of different projects is achieved by bi-annual workshops, common procedures imposed by the integrative project, by researchers working on different component projects and the organization of discussion boards.